1. Field of the Invention
The present invention relates to the field of semiconductor production, particularly to a reaction apparatus for wafer treatment, an electrostatic chuck (ESC) and a wafer temperature control method.
2. Description of the Related Art
The wafer (such as silicon wafer) is a foundational semiconductor material for die fabrication, and is also the most important material in the semiconductor industry. The final quality of dies produced from wafers is directly influenced by the quality of wafers initially employed in their fabrication. If initial wafers are defective, dies produced therefrom will inevitably have some defects. Thus, strict material and physical requirements must be maintained for wafers that can be employed in semiconductor device fabrication.
Cost is also a critical factor in the semiconductor industry. From the perspective of cost, modern semiconductor techniques seek on one hand to reduce the physical size of devices produced from wafers, and on the other hand make great efforts to enlarge wafer size, both of which are intended to produce more dies at approximately the same costs. With the development of larger wafers, for example 5 inch, 8 inch and now 12 inch, and a next generation with 18 inch or even larger sizes, various new issues arise.
Uniformity control is an important aspect in wafer processes. The larger the size of the wafers, the more critical the uniformity control; uniformity control has become a major challenge in the development of those processes.
An ESC cooling system is an important means used in wafer temperature uniformity control. Existing ESC cooling systems employ a ring type multi-zone design, which can provide different temperatures for different cooling zones to adjust the temperature uniformity of the wafers. Such designs can favourably adjust for radial temperature non-uniformity. However, such existing ESC designs are unable to provide appropriate adjustment of temperature non-uniformity in the non-radial direction. FIG. 1A-FIG. 1C show an adjustment result for non-uniform temperature distribution of the existing ESC design, wherein FIG. 1A shows a greyscale temperature distribution (C.°) across a wafer to be treated, FIG. 1B shows a tuned distribution of the temperature profile after adjustment with an existing ESC design and FIG. 1C shows the temperature differences between FIG. 1A and FIG. 1B illustrating that non-radial locations can't be tuned. As shown in FIG. 1A-FIG. 1C, the ESC design can adjust radial temperature distribution non-uniformity, but fails to adjust non-radial non-uniformity appropriately, and may lead to an even greater variation range of temperature. Furthermore, the existing cooling system can not provide adequate temperature control accuracy.